1. Field of the Invention
This invention pertains in general to computer security and in particular to generating behavioral signatures for detecting malicious software.
2. Description of the Related Art
There is a wide variety of malicious software (malware) that can attack modern computers. Malware threats include computer viruses, worms, Trojan horse programs, spyware, adware, crimeware, and phishing websites. Malware can, for example, surreptitiously capture important information such as logins, passwords, bank account identifiers, and credit card numbers. Similarly, the malware can provide hidden interfaces that allow the attacker to access and control the compromised computer.
Modern malware is often targeted and delivered to only a relative handful of computers. For example, a Trojan horse program can be designed to target computers in a particular department of a particular enterprise. Such malware is difficult for security software to detect because there are fewer instances of the same malware, and the security software might not be configured to recognize it. Moreover, even mass-distributed malware is becoming harder to detect because the malware can contain polymorphisms designed to evade detection.
In response to the increasing difficulty of detecting malware, security software is evolving toward heuristics-based detection. This type of detection uses a set of heuristics, such as behavioral signatures that describe behaviors indicative of malicious behavior, to identify malware. However, the huge amount of different malware makes it difficult to maintain behavioral signatures for the malware. Having many behavioral signatures introduces complexities in maintaining and using the signatures. For example, the analyses used to determine whether a piece of software is malicious grow more complex, and the computational resources consumed to make this determination increase, as the number of behavioral signatures increases.